The present invention relates generally to image forming apparatuses, and more particularly to an image forming apparatus which forms a predetermined image on each recording paper of a plurality of recording papers and ejects each recording paper therefrom through a feed path, such as a facsimile equipment unit, a laser printer, a copying machine, or the like.
In a conventional electrophotograph recording apparatus shown in FIG. 1, a predetermined image is transferred on the recording paper 12 from a recording paper cassette 11 by a developing roller 8 before it is ejected to a tray 21. A brief description will now be given of a conventional image forming process of the electrophotograph recording apparatus with reference to FIG. 1. The electrophotograph recording apparatus generally uses a rotary polygon mirror 5 for sweeping among the plane scanning methods. A laser beam appropriate to image signals from a laser beam unit is reflected on the polygon mirror 5 so as to be irradiated to the photosensitive (photoconductive) belt 1 via a mirror 6 and a plastic cylindrical lens 7 in a exposure unit 4 to form a static latent image thereon. The photosensitive belt 1, moved around by driving rollers 2, is charged with electricity by a precharger 3 in advance of the transferring operation. The latent image on the photosensitive belt 1 is developed by the developing roller 8 with toner supplied from a toner cartridge 9 and a hopper 10. On the other hand, the recording paper 12 is fed at a proper time from the recording paper cassette 11 to a transfer charger 17 so that the image can be transferred thereon, via a pickup roller 13, a feed roller 14, a separate roller 15 and a pair of resist rollers 16. The feed roller 14 feeds the uppermost recording paper from among the recording papers fed by the pickup roller 13 which is coupled to the recording paper cassette 11. And the separating roller 15, coupled to the feed roller 14, separates the recording paper 12 from the pile of recording papers. After being transferred, the recording paper 12 is ejected to a tray 21 via a fixing roller 18, a pushing roller 19, and a pair of ejecting rollers 20. The fixing roller 18, a part of the fixing apparatus (not shown), has a heater therein to fix the predetermined image on the recording paper 12. And the push roller 19, coupled to the fixing roller 18, pushes the fixing roller 18 so as to fix the predetermined image on the recording paper 12. Meanwhile, the remains of the toner on the photosensitive belt 1 is removed by a cleaning blade 22 in a toner recovery chamber 23, and then the cleaned photosensitive belt 1 is discharged by a discharge lamp 24 to prepare for the next process.
Hereupon, the electrophotograph recording apparatus in FIG. 1 conventionally comprises a lower unit and an upper unit coupled to the lower unit pivotably around a fulcrum 25, as shown in FIG. 2, so that the upper unit can be opened in case the recording paper 12 is jammed. As shown in FIG. 2, the upper unit includes many parts of the electrophotograph recording apparatus, such as the photosensitive belt 1, the exposure unit 4, and the discharge lamp 24, which are described above, and moreover, a paper supply roller, a reading lens, a charged-coupled device (called for short CCD) image sensor and the like.
On the other hand, it is required that the conventional electrophotograph recording apparatus is opened even when the toner cartridge 9 and/or the toner recovery chamber 23 are exchanged. Therefore, they must be placed to face an opening of the electrophotograph recording apparatus so they can be exchanged easily.
However, the conventional electrophotograph recording apparatus has the following disadvantages.
1. It is troublesome to open the heavy upper unit having many parts therein.
2. It is necessary to provide a safety device for preventing the upper unit from colliding with the lower unit while the upper unit is being opened, however, such a device costs a lot.
3. A developing unit comprising the developing roller 8, toner cartridge 9, and hopper 10 and the toner recovery chamber 23 are facing the opening so that they obstruct the way by which the jammed recording paper is removed.
4. It is difficult to place a book scanner on the upper surface of the electrophotograph recording apparatus in order to prevent the upper unit from increasing its weight.